Hyperglycosylated human chorionic gonadotropin and the source of pregnancy failures

Objective

To investigate the proportion of hyperglycosylated human chorionic gonadotropin (hCG-H) produced at the time of implantation as a predictor of pregnancy success.

Design

Measuring daily urine hCG and hCG-H on the day of implantation. The time of implantation was assumed to be the first day of hCG detection (total hCG >1 mIU/mL).

Setting

Urine samples were collected at volunteers' homes throughout city of Albuquerque.

Patient(s)

110 women attempting to conceive spontaneously; 62 achieved pregnancies (42 to term and 20 failed).

Intervention(s)

None.

Main Outcome Measure(s)

Measurements of the total hCG and hCG-H, and calculations of the proportion of hCG-H.

Result(s)

In all 42 term pregnancies, the proportion of hCG-H on the day of implantation was >50%. This was also true for 7 of the 20 failures. Statistically significant lower proportions of hCG-H (<50%) were observed in 13 of 20 pregnancies that eventually failed. The predictive values of proportion of hCG-H, concentration of hCG-H, total hCG, and regular hCG alone for detecting failures were 100%, 59%, 41%, and 21%, respectively.

Conclusion(s)

Hyperglycosylated is produced by cytotrophoblast cells in early pregnancy at the time of implantation. Effective proportions of hCG-H (>50%) are required for successful growth and invasion by cytotrophoblasts at the time of implantation. Low proportions of hCG-H at implantation predict failure and are likely to be the root of many pregnancy failures. The 7 of 20 failures with normal proportions of hCG-H were likely due to genetic, immune, or maternal causes. Measurement of a proportion of hCG-H <50% on the day of implantation absolutely indicates a failing pregnancy.

Key Words: Implantation, hCG, hyperglycosylated hCG, pregnancy failure, spontaneous abortion